Piperidine compounds and their use as anti-oxidative, light or thermal induced degradation agents

ABSTRACT

Compounds of formula (I) ##STR1## in which R 1  is hydrogen, O.sup.., CN, NO, cyanomethyl, C 1  -C 12  -alkyl, C 3  -C 12  -alkenyl or C 3  -C 12  -alkynyl subject to the proviso that the carbon atom attached to the nitrogen atom is a primary carbon atom, C 7  -C 12  -aralkyl, C 1  -C 12  -acyl, 2,3-epoxypropyl, OH-monosubstituted C 2  -C 6  -alkyl or 2,3-dihydroxypropyl, R 2  is hydrogen, C 1  -C 18  -alkyl, C 5  -C 18  -cycloalkyl, C 6  -Chd 18-aryl or C 7  -C 18  -aralkyl, R 3  is C 6  -C 18  -aryl or a group of the formula (II) ##STR2## in which R 1  is as defined above, n is an integer from 1 to 4 and R 4  is an organic or inorganic radical of a valency equal to n are useful for stabilizing organic material against oxidative, thermal and/or light induced degradation.

The present invention relates to novel piperidine compounds, the use thereof and to the organic material stabilized with the aid of said compounds against thermal, oxidative and/or light induced degradation.

It is known that synthethic polymers undergo progressive changes in their physical properties, such as loss of mechanical strength and colour changes, when they are exposed to sunlight or other sources of ultraviolet light. To retard the deleterious effect of sunlight on synthetic polymers, it has been proposed to use various additives having light-stabilizing properties.

FR No. 2 268 011 describes substituted N,N'-diphenylformamidine compounds and the use thereof as light stabilizers. JP No. 85-84258 discloses a process for the preparation of substituted N,N'-formamidine derivatives.

The present invention relates to novel piperidine compounds of the formula (I) ##STR3## in which R₁ is hydrogen, O.sup.·, CN, NO, cyanomethyl, C₁ -C₁₂ -alkyl, C₃ -C₁₂ -alkenyl or C₃ -C₁₂ -alkynyl subject to the proviso that the carbon atom attached to the nitrogen atom is a primary carbon atom, C₇ -C₁₂ -aralkyl, C₁ -C₁₂ -acyl, 2,3-epoxypropyl, OH-monosubstituted C₂ -C₆ -alkyl or 2,3-dihydroxypropyl, R₂ is hydrogen, C₁ -C₁₈ -alkyl, C₅ -C₁₈ -cycloalkyl, C₆ -C₁₈ -aryl or C₇ -C₁₈ -aralkyl, R₃ is C₆ -C₁₈ -aryl or a group of the formula (II) ##STR4## in which R₁ is as defined above, n is an integer from 1 to 4 and R₄ is an organic or inorganic radical of a valency equal to n.

If n is 1, R₄ is preferably selected from the group consisting of hydrogen, CN, ##STR5## in which R₅ is hydrogen, C₁ -C₁₈ -alkyl, C₅ -C₁₈ -cycloalkyl, C₂ -C₁₈ -alkenyl, C₆ -C₁₈ -aryl, C₇ -C₁₈ -aralkyl or C₁ -C₁₀ -alkyl substituted by C₁ -C₁₈ -alkoxy, by C₂ -C₁₈ -dialkylamino or by a group of the formula (III) ##STR6## where R₁ is as defined above and W is --O-- or ##STR7## where R₁₅ is hydrogen, C₁ -C₁₈ -alkyl, C₅ -C₁₈ -cycloalkyl, C₃ -C₁₈ -alkenyl, C₆ -C₁₈ -aryl, C₇ -C₁₈ -aralkyl or a group of the formula (II), R₆ is C₁ -C₁₈ -alkyl, C₂ -C₆ -alkyl substituted by OH, by C₁ -C₁₈ -alkoxy or by C₂ -C₁₈ -dialkylamino, C₅ -C₁₈ -cycloalkyl, C₃ -C₁₈ -alkenyl, C₆ -C₁₈ -aryl, C₇ -C₁₈ -aralkyl or a group of the formula (II), R₇ is a direct bond, C₁ -C₁₈ -alkylene, C₂ -C₂₀ -alkylidene, C₇ -C₂₀ -aralkylidene, C₆ -C₁₀ -cycloalkylene, C₂ -C₁₈ -alkenylene or C₆ -C₁₀ -arylene, R₈ is as defined for R₆ or is hydrogen or an alkali metal, R₉ and R₁₀, which are identical or different, are as defined for R₁₅, or R₉ and R₁₀, together with the nitrogen atom to which they are bonded, form part of a 5-membered to 7-membered heterocyclic ring, R₁₁ is C₁ -C₁₂ -alkyl or C₆ -C₁₂ -aryl, r is 0 or 1, R₁₂ is C₁ -C₁₂ -alkyl or a group of the formula (II), or the two groups R₁₂ together are C₂ -C₁₂ -alkylene or C₆ -C₂₈ -arylene and together with the phosphorus atom and the two oxygen atoms form a 5-membered to 7-membered ring, R₁₃ and R₁₄, which can be identical or different, are as defined for R₆ or are hydrogen, and X and Y, which can be identical or different, are a direct bond, --O-- or ##STR8## where R₁₆ is as defined for R₁₅ or is OH-monosubstituted C₂ -C₆ -alkyl, or the groups R₁₃ X-- and R₁₄ Y--, which can be identical or different, are a 5-membered to 7-membered heterocyclic group.

If n is 2, R₄ is preferably selected from the group consisting of ##STR9## in which R₁₇ is C₂ -C₁₈ -alkylene, C₄ -C₁₂ -alkylene substituted in the chain by 1 or 2 oxygen atoms, C₆ -C₁₈ -cycloalkylene, C₄ -C₈ -alkenylene, C₆ -C₁₈ -arylene, C₈ -C₁₂ -aralkylene or a group of the formula (IV) ##STR10## where R₂₃ is hydrogen, C₁ -C₄ -alkyl or phenyl, R₁₈ is a direct bond, C_(1-C) ₁₈ -alkylene, C₂ -C₂₀ -alkylidene, C₇ -C₂₀ -aralkylidene, C₆ -C₁₀ -cycloalkylene, C₆ -C₁₀ -arylene, C₂ -C₁₂ -alkylene substituted in the chain by 1 or 2 oxygen atoms or by 1 or 2 groups ##STR11## where R₂₄ is as defined for R₁₅, R₁₉ and R₂₁, which can be identical or different, are as defined for R₁₅, R₂₀ is C₂ -C₁₈ -alkylene, C₆ -C₁₈ -cycloalkylene, C₆ -C₁₈ -arylene or C₈ -C₁₂ -aralkylene, R₂₂ is as defined for R₁₃ and R₁₄, Z is as defined for X and Y, or --ZR₃₃ is a 5-membered to 7-membered heterocyclic group or halogen, R₂₅ is C₁ -C₄ -alkyl, s is 0 or 1, R₇ is as defined above and Me is Ba, Ca, Co", Mg, Mn", Ni", Sn" or Zn.

If n is 3, R₄ is preferably selected from the group consisting of aliphatic C₄ -C₁₈ -triacyl, aliphatic C₆ -C₁₈ -triacyl substituted by a nitrogen atom, aromatic or heterocyclic triacyl having up to 18 carbon atoms, substituted aliphatic, aromatic or heterocyclic tricarbamoyl having up to 24 carbon atoms, a 1,3,5-triazine-2,4,6-triyl group, a .tbd.P group, a .tbd.PO group and a group (--CO-R₇ --COO)₃ Al with R₇ as defined above.

If n is 4, R₄ is preferably selected from the group consisting of aliphatic C₆ -C₁₈ -tetraacyl, aliphatic C₁₀ -C₁₈ -tetraacyl substituted by two nitrogen atoms, aromatic C₁₀ -C₁₈ -tetraacyl, cycloaliphatic C₁₀ -C₂₂ -tetraacyl and a group (--CO--R₇ --COO)₄ Sn^(IV), where R₇ is as defined above.

R₁, R₁₁ and R₁₂ as C₁ -C₁₂ -alkyl are for example methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, decyl or dodecyl. C₁ -C₄ -alkyl which may be straight or branched is preferred. R¹ as methyl is especially preferred.

R₁ as C₃ -C₁₂ -alkenyl is for example allyl, 2-methallyl, 2-butenyl, 2-hexenyl or 10-undecenyl. Allyl is especially preferred.

R₁ as C₃ -C₁₂ -alkynyl may be preferably propargyl.

R₁ as C₇ -C₁₂ -aralkyl is for example benzyl, methylbenzyl, t-butylbenzyl or hydroxybenzyl. C₇ -C₁₀ -phenylalkyl unsubstituted or substituted at the phenyl ring by alkyl and/or by OH is preferred. Benzyl and benzyl substituted by C₁ -C₄ -alkyl and/or by OH are especially preferred.

R₁ as C₁ -C₁₂ -acyl may be an aliphatic or aromatic C₁ -C₁₂ -acyl group. C₁ -C₁₂ -alkanoyl, C₃ -C₁₂ -alkenoyl, C₃ -C₁₂ -alkynoyl, benzoyl and benzoyl substituted by C₁ -C₄ -alkyl and/or by OH are preferred. Examples are formyl, acetyl, propionyl, butyryl, caproyl, capryloyl, caprinoyl, lauroyl, benzoyl, acryloyl, methacryloyl and crontonyl.

R₁, R₆, R₁₃, R₁₄, R₁₆ and R₂₂ as OH-monosubstituted C₂ -C₆ -alkyl are for example 2-hydroxyethyl, 2-hydroxypropyl or 3-hydroxypropyl.

R₂, R₅, R₆, R₈, R₉, R₁₀, R₁₃, R₁₄, R₁₅, R₁₆, R₁₉, R₂₁, R₂₂ and R₂₄ as C₁ -C₁₈ -alkyl are for example methyl, ethyl, propyl, isopropyl, butyl, isobutyl, 2-butyl, t-butyl, pentyl, isopentyl, hexyl, heptyl, 3-heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, octadecyl or heptadecyl. R₂ is preferably C₁ -C₄ -alkyl, in particular methyl.

R₂, R₅, R₆, R₈, R₉, R₁₀, R₁₃, R₁₄, R₁₅, R₁₆, R₁₉, R₂₁, R₂₂ and R₂₄ as C₅ -C₁₈ -cycloalkyl are preferably a cycloalkyl group of the formula --HC (CH₂)_(a) with a being an integer from 4 to 11. Said cycloalkyl group may optionally be substituted by C₁ -C₄ -alkyl. Examples are cyclopentyl, cyclohexyl, methylcyclohexyl, dimethylcyclohexyl, trimethylcyclohexyl, t-butylcyclohexyl, cyclooctyl and cyclododecyl. Cyclohexyl unsubstituted or substituted by C₁ -C₄ -alkyl is especially preferred.

R₂, R₃, R₅, R₆, R₈, R₉, R₁₀, R₁₃, R₁₄, R₁₅, R₁₆, R₁₉, R₂₁, R₂₂ and R₂₄ as C₆ -C₁₈ -aryl are for example phenyl or naphthyl which both may be substituted or unsubstituted.

R₃ as C₆ -C₁₈ -aryl may be preferably phenyl unsubstituted or substituted by C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy, C₂ -C₄ -alkoxycarbonyl and/or OH, or may be phenyl substituted by 2,2,6,6-tetramethyl-4-piperidyloxycarbonyl or by 1,2,2,6,6-pentamethyl-4-piperidyloxycarbonyl. Preferred examples of R₃ are phenyl, methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl, diethylphenyl, hydroxyphenyl, 3,5-di-t-butyl-4-hydroxyphenyl, methoxyphenyl, ethoxyphenyl, 4-ethoxycarbonylphenyl, 4-(2,2,6,6-tetramethyl-4-piperidyloxycarbonyl)phenyl and 4-(1,2,2,6,6-pentamethyl-4-piperidyloxycarbonyl)phenyl.

R₂, R₅, R₉, R₁₀, R₁₅, R₁₆, R₁₉, R₂₁ and R₂₄ as C₆ -C₁₈ -aryl may be preferably phenyl unsubstituted or substituted by C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy and/or OH, or may be naphthyl unsubstituted or substituted by C₁ -C₄ -alkoxy. Preferred examples of R₂, R₅, R₉, R₁₀, R₁₅, R₁₆, R₁₉, R₂₁ and R₂₄ are phenyl, methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl, t-butylphenyl, methoxyphenyl, ethoxyphenyl, hydroxyphenyl and 3,5-di-t-butyl-4-hydroxyphenyl with phenyl being especially preferred.

R₆, R₈, R₁₃, R₁₄ and R₂₂ as C₆ -C₁₈ -aryl may be preferably phenyl unsubstituted or substituted by C₁ -C₄ -alkyl and/or alkoxy, or may be naphthyl unsubstituted or substituted by C₁ -C₄ -alkoxy. Preferred examples of R₆, R₈, R₁₃, R₁₄ and R₂₂ are phenyl, methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl, isopropylphenyl, t-butylphenyl, di-t-butylphenyl, 2,6-di-t-butyl-4-methylphenyl, methoxyphenyl and ethoxyphenyl.

R₂, R₅, R₆, R₈, R₉, R₁₀, R₁₃, R₁₄, R₁₅, R₁₆, R₁₉, R₂₁, R₂₂ and R₂₄ as C₇ -C₁₈ -aralkyl may be C₇ -C₁₀ -phenylalkyl unsubstituted or substituted at the phenyl ring by C₁ -C₄ -alkyl and/or OH. Examples are benzyl, methylbenzyl, hydroxybenzyl, 3,5-di-t-butyl-4-hydroxybenzyl and 2-(3,5-di-t-butyl-4-hydroxyphenyl)ethyl. Benzyl unsubstituted or substituted is preferred.

R₅ as C₂ -C₁₈ -alkenyl is for example vinyl, propenyl, allyl, butenyl, methylallyl, hexenyl, decenyl or heptadecenyl.

R₅ as C₁ -C₁₀ -alkyl which is substituted by C₁ -C₁₈ -alkoxy or C₂ -C₁₈ -dialkylamino is for example ethoxymethyl, butoxymethyl, octoxyethyl, 2-ethoxyethyl, 3-butoxyethyl, 3-methoxypropyl, 3-butoxypropyl, diethylaminomethyl, dibutylaminomethyl, 2-diethylaminoethyl, 2-dibutylaminoethyl or 3-diethylaminopropyl.

R₆, R₈, R₁₃, R₁₄ and R₂₂ as C₂ -C₆ -alkyl which is substituted by C₁ -C₁₈ -alkoxy or C₂ -C₁₈ -dialkylamino are for example 2-methoxyethyl, 2-ethoxyethyl, 2-butoxyethyl, 2-octoxyethyl, 3-ethoxypropyl, 3-butoxypropyl, 4-butoxybutyl, 2-diethylaminoethyl, 2-dibutylaminoethyl or 3-dibutylaminopropyl.

R₆, R₈, R₉, R₁₀, R₁₃, R₁₄, R₁₅, R₁₆, R₁₉, R₂₁, R₂₂ and R₂₄ as C₃ -C₁₈ -alkenyl are for example allyl, butenyl, methylallyl, hexenyl, decenyl, undecenyl or oleyl.

R₇ and R₁₈ as C₁ -C₁₈ -alkylene are for example methylene, ethylene, propylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, decamethylene or dodecamethylene. C₁ -C₆ -alkylene is preferred. Ethylene is especially preferred.

R₇ and R₁₈ as C₂ -C₂₀ -alkylidene are for example ethylidene, propylidene, butylidene, pentylidene, 4-methylpentylidene, heptylidene, nonylidene, tridecylidene, nonadecylidene, 1-methylethylidene, 1-ethylpropylidene or 1-ethylpentylidene.

R₇ and R₁₈ as C₇ -C₂₀ -aralkylidene may be C₇ -C₂₀ -phenylalkylidene such as for example benzylidene, 2-phenylethylidene or 1-phenyl-2-hexylidene.

R₇ and R₁₈ as C₆ -C₁₀ -cycloalkylene and R₁₇ and R₂₀ as C₆ -C₁₈ -cycloalkylene may be a saturated hydrocarbon group with two free valencies and at least one cyclic unit.

R₇, R₁₇, R₁₈ and R₂₀ are for example cyclohexylene or cyclohexylene substituted by C₁ -C₄ -alkyl. Cyclohexylene and methylcyclohexylene are preferred.

In addition R₁₇ and R₂₀ may be alkylene-cyclohexylene-alkylene with 8 to 18 carbon atoms, cyclohexylene-alkylene-cyclohexylene with 13 to 18 carbon atoms or alkylidenedicyclohexylene with 14 to 18 carbon atoms. Preferred examples are cyclohexylenedimethylene, methylenedicyclohexylene, isopropylidenedicyclohexylene.

R₇ as C₂ -C₁₈ -alkyenylene is for example vinylene, methylvinylene, octenylethylene or dodecenylethylene.

R₇ and R₁₈ as C₆ -C₁₀ -arylene and R₁₇ and R₂₀ as C₆ -C₁₈ -arylene may be substituted or unsubstituted at the aromatic group. R₇ and R₁₈ are for example 1,2-phenylene, 1,3-phenylene or 1,4-phenylene. R₁₇ and R₂₀ are preferably phenylene unsubstituted or substituted by C₁ -C₄ -alkyl, biphenylene, phenylene-alkylene-phenylene with 13 to 18 carbon atoms, phenylene-alkylidene-phenylene with 14 to 18 carbon atoms, naphthylene. Preferred examples are phenylene, methylphenylene, biphenylene, methylenediphenylene, isopropylidenediphenylene.

R₈ as alkalimetal may be Li, Na or K.

If R₉ and R₁₀ together with the nitrogen atom to which they are bonded form part of a 5-membered to 7-membered heterocyclic group, this group is preferably a saturated heterocyclic group with N and/or O as hetero atoms. Illustrative examples are 1-pyrrolidinyl, 1-piperidyl, 4-morpholinyl, 1hexahydroazepinyl and 4-methyl-1-piperazinyl.

R₁₁ as C₆ -C₁₂ -aryl is for example phenyl or naphthyl which both may be substituted or unsubstituted. R₁₁ is preferably phenyl unsubstituted or substituted by C₁ -C₃ -alkyl and/or C₁ -C₃ -alkoxy. Examples are phenyl, methylphenyl, dimethylphenyl, trimethylphenyl, methoxyphenyl and ethoxyphenyl.

If the two groups R₁₂ together are C₂ -C₁₂ -alkylene or C₆ -C₂₈ -arylene and together with the phosphorus atom and the two oxygen atoms form a 5-membered to 7-membered heterocyclic ring, the C₂ -C₁₂ -alkylene group is preferably a straight chain or branched alkylene group with 2 to 7 carbon atoms and the C₆ -C₂₈ -arylene group may be a 1,2-phenylene group unsubstituted or substituted by C₁ -C₄ -alkyl or may be a biphenylene group unsubstituted or substituted by C₁ -C₄ -alkyl.

Examples for R₄ as a group ##STR12## are: ##STR13## --XR₁₃, --YR₁₄ and -ZR₂₂ as a 5-membered to 7-membered heterocyclic group may be a saturated heterocyclic group with N and/or O as hetero atoms. Illustrative examples are 1-pyrrolidinyl, 1-piperidyl, 4-morpholinyl, 1-hexahydroazepinyl and 4-methyl-1-piperazinyl.

--ZR₂₂ may also be halogen, preferably Cl.

R₁₇ and R₂₀ as C₂ -C₁₈ -alkylene are for example ethylene, propylene, trimethylene, tetramethylene, pentamethylene, 2,2-dimethyl-1,3-propanediyl, hexamethylene, octamethylene, decamethylene or dodecamethylene. C₂ -C₆ -alkylene is preferred.

R₁₇ as C₄ -C₁₂ -alkylene which is substituted in the chain by 1 or 2 oxygen atoms is for example 3-oxapentane-1,5-diyl or 3,6-dioxaoctane-1,8-diyl.

R₁₇ as C₄ -C₈ -alkenylene is for example 2-butene-1,4-diyl.

R₁₇ and R₂₀ as C₈ -C₁₂ -aralkylene are for example alkylene-phenylenealkylene with 8 to 12 carbon atoms, preferably dimethylenephenylene (xylylene) which may optionally be substituted by C₁ -C₄ -alkyl.

R₁₈ as C₂ -C₁₂ -alkylene which is substituted in the chain by 1 or 2 oxygen atoms is for example 2-oxapropane-1,3-diyl, 2,7-dioxaoctane-1,8-diyl or 2,6-dioxa-4,4-dimethyl-1,7-heptanediyl.

R₂₃ and R₂₅ as C₁ -C₄ -alkyl are for example methyl, ethyl, propyl or butyl.

R₄ as aliphatic C₄ -C₁₈ -triacyl may be C₄ -C₁₈ -alkanetrioyl unsubstituted or substituted by OH. Preferred examples are those triacyls derived from methanetricarboxylic, 1,1,2-ethanetricarboxylic, 1,2,3-propanetricarboxylic, citric or 1,2,3-butanetricarboxylic acids.

R₄ as aliphatic C₆ -C₁₈ -triacyl which is substituted by a nitrogen atom is for example ##STR14##

The group N(CH₂ CO--)₃ is especially preferred.

R₄ as aromatic triacyl having up to 18 carbon atoms is for example a triacyl derived from 1,2,4-benzenetricarboxylic acid or 1,3,5-benzenetricarboxylic acid.

R₄ as heterocyclic triacyl having up to 18 carbon atoms is for example ##STR15##

A heterocyclic triacyl group with 9 to 12 carbon atoms is preferred.

R₄ as substituted aliphatic tricarbamoyl having up to 24 carbon atoms is for example a group ##STR16## with d being an integer from 2 6, preferably 6.

R₄ as aromatic tricarbamoyl having up to 24 carbon atoms is for example benzenetricarbamoyl.

R₄ as heterocyclic tricarbamoyl having up to 24 carbon atoms is for example a group ##STR17## with e being an integer from 2 to 6, preferably 6.

R₄ as aliphatic C₆ -C₁₈ -tetraacyl may be C₄ -C₁₈ -alkanetetraoyl. Preferred examples are those tetraacyls derived from 1,1,3,3-propanetetracarboxylic or 1,2,3,4-butanetetracarboxylic acids.

R₄ as aliphatic C₁₀ -C₁₈ -tetraacyl which is substituted with two nitrogen atoms is for example a group of the formula ##STR18##

A tetraacyl derived from ethylenediaminetetraacetic acid is preferred.

R₄ as aromatic C₁₀ -C₁₈ -tetraacyl is for example the tetraacyl derived from 1,2,4,5-benzenetetracarboxylic acid.

R₄ as cycloaliphatic C₁₀ -C₂₂ -tetraacyl may be a cycloalkanetetracarbonyl with 10 to 22 carbon atoms or a cycloalkenetetracarbonyl with 10 to 22 carbon atoms. Examples are the following groups: ##STR19##

Those compounds of formula (I) are preferred, in which R₁ is hydrogen, methyl, allyl, benzyl or acetyl, R₂ is hydrogen, C₁ -C₁₂ -alkyl, C₆ -C₉ -cycloalkyl or C₆ -C₉ -aryl, R₃ is C₆ -C₁₂ -aryl or a group of the formula (II), n is 1, 2 or 3 and, if n is 1, R₄ is hydrogen, ##STR20## in which R₅ is hydrogen, C₁ -C₁₈ -alkyl, C₆ -C₉ -cycloalkyl, C₂ -C₄ -alkenyl, C₆ -C₈ -aryl, C₇ -C₁₆ -aralkyl or C₁ -C₃ -alkyl substituted by a group of the formula (III) where W is --O-- or ##STR21## and R₁₅ is hydrogen, C₁ -C₁₂ -alkyl or C₆ -C₉ -cycloalkyl, R₆ is C₁ -C₁₈ -alkyl, C₂ -C₆ -alkyl substituted by C₁ -C₄ -alkoxy, C₆ -C₁₂ -cycloalkyl or a group of the formula (II), R₇ is a direct bond, C₁ -C₁₀ -alkylene, C₆ -C₈ -cycloalkylene, vinylene or phenylene, R₈ is hydrogen, C₁ -C₁₂ -alkyl, C₆ -C₉ -cycloalkyl, allyl or a group of the formula (II), R₉ and R₁₀, which are identical or different, are hydrogen, C₁ -C₁₂ -alkyl, C₆ -C₉ -cycloalkyl, allyl or a group of the formula (II), or, together with the nitrogen atom to which they are bonded, form part of a heterocyclic ring, R₁₁ is methyl, ethyl or C₆ -C₉ -aryl, R₁₃ and R₁₄, which are identical or different, are hydrogen, C₁ -C₁₂ -alkyl, C₆ -C₉ -cycloalkyl, allyl or a group of the formula (II), X and Y, which are identical or different, are --O-- or ##STR22## where R₁₆ is hydrogen, C₁ -C₁₂ -alkyl, OH-monosubstituted C₂ -C₄ -alkyl, C₆ -C₉ -cycloalkyl, allyl or a group of the formula (II), or the groups R₁₃ X-- and R₁₄ Y--, which are identical or different, are a 1-pyrrolidinyl, 1-piperidyl, 4-morpholinyl or 1-hexahydroazepinyl group or, if n is 2, R₄ is --CO--, ##STR23## in which R₁₇ is C₂ -C₁₂ -alkylene, C₄ -C₁₂ -alkylene substituted in the chain by 1 or 2 oxygen atoms, C₆ -C₁₅ -cycloalkylene, 2-butene-1,4-diyl or a group of the formula (IV) in which R₂₃ is hydrogen or methyl, R₁₈ is a direct bond, C₁ -C₁₂ -alkylene, C₂ -C₁₂ -alkylidene, C₂ -C₈ -alkylene substituted in the chain by one or two groups ##STR24## where R₂₄ is C₁ -C₈ -alkyl, C₆ -C₉ -cycloalkyl or a group of the formula (II), R₁₉ and R₂₁, which are identical or different, are hydrogen, C₁ -C₈ -alkyl, C₆ -C₉ -cycloalkyl or a group of the formula (II), R₂₀ is C₂ -C₁₀ -alkylene, C₆ -C₁₅ -cycloalkylene, C₆ -C₁₅ -arylene or xylylene, R₂₂ is hydrogen, C₁ -C₁₂ -alkyl, OH-monosubstituted C₂ -C₄ -alkyl, C₆ -C₉ -cycloalkyl, allyl or a group of the formula (II) and Z is --O-- or ##STR25## with R₁₆ as defined above, or --ZR₂₂ is halogen, R₂₅ is C₁ -C₄ -alkyl and, if n is 3, R₄ is aliphatic C₄ -C₈ -triacyl, a group N(CH₂ CO--)₃, aromatic or heterocyclic triacyl having up to 10 carbon atoms or a 1,3,5-triazine-2,4,6-triyl group.

Those compounds of formula (I) are preferred, in which R₁ is hydrogen, methyl, allyl, benzyl or acetyl, R₂ is hydrogen, C₁ -C₁₂ -alkyl, C₆ -C₉ -cycloalkyl or C₆ -C₉ -aryl, R₃ is C₆ -C₁₂ -aryl or a group of the formula (II), n is 1, 2 or 3 and, if n is 1, R₄ is hydrogen or one of the groups ##STR26## in which R₅ is hydrogen, C₁ -C₁₈ -alkyl, C₆ -C₉ -cycloalkyl, C₂ -C₄ -alkenyl, C₆ -C₈ -aryl, C₇ -C₁₆ -aralkyl or C₁ -C₃ -alkyl substituted by a group of the formula (III) where W is --O-- or ##STR27## and R₁₅ is hydrogen, C₁ -C₁₂ -alkyl or C₆ -C₉ -cycloalkyl, R₆ is C₁ -C₁₂ -alkyl, C₆ -C₁₂ -cycloalkyl or a group of the formula (II), R₇ is a direct bond, C₁ -C₈ -alkylene, C₆ -C₈ -cycloalkylene, vinylene or phenylene, R₈ is C₁ -C₁₂ -alkyl, C₆ -C₉ -cycloalkyl, allyl or a group of the formula (II), R₉ and R₁₀, which can be identical or different, are hydrogen, C₁ -C₁₂ -alkyl, C₆ -C₉ -cycloalkyl, allyl or a group of the formula (II), or, together with the nitrogen atom to which they are bonded, form part of a heterocyclic ring, such as pyrrolidine, piperidine, morpholine or hexahydroazepine, R₁₁ is methyl, ethyl or C₆ -C₉ -aryl, R₁₃ and R₁₄, which can be identical or different, are hydrogen, C₁ -C₁₂ -alkyl, C₆ -C₉ -cycloalkyl, allyl or a group of the formula (II), X and Y, which can be identical or different, are --O-- or ##STR28## where R₁₆ is hydrogen, C₁ -C₁₂ -alkyl, C₆ -C₉ -cycloalkyl, allyl or a group of the formula (II), or the groups R₁₃ X-- and R₁₄ Y--, which can be identical or different, are a 1-pyrrolidinyl, 1-piperidyl, 4-morpholinyl or 1-hexahydroazepinyl group or, if n is 2, R₄ is a --CO-- group or one of the groups ##STR29## in which R₁₇ is C₂ -C₁₀ -alkylene, C₆ -C₁₅ -cycloalkylene, 2-butene-1,4-diyl or a group of the formula (IV) in which R₂₃ is hydrogen or methyl, R₁₈ is a direct bond, C₁ -C₁₂ -alkylene, C₂ -C₁₂ -alkylidene, C₂ -C₈ -alkylene substituted in the chain by one or two groups ##STR30## where R₂₄ is C₁ -C₈ -alkyl, C₆ -C₉ -cycloalkyl or a group of the formula (II), R₁₉ and R₂₁, which can be identical or different, are hydrogen, C₁ -C₈ -alkyl, C₆ -C₉ -cycloalkyl or a group of the formula (II), R₂₀ is C₂ -C₁₀ -alkylene, C₆ -C₁₅ -cycloalkylene, C₆ -C₁₅ -arylene or xylylene, R₂₂ is hydrogen, C₁ -C₁₂ -alkyl, C₆ -C₉ -cycloalkyl, allyl or a group of the formula (II) and Z is --O-- or ##STR31## with R₁₆ as defined above, or, if n is 3, R₄ is aliphatic C₄ -C₈ -triacyl, a group N(CH₂ CO--)₃, aromatic or heterocyclic triacyl having up to 10 carbon atoms or a 1,3,5-triazine-2,4,6-triyl group.

Those compounds of formula (I) are particularly preferred, in which R₁ is hydrogen or methyl, R₂ is hydrogen or methyl, R₃ is 2,2,6,6-tetramethyl-4-piperidyl or 1,2,2,6,6-pentamethyl-4-piperidyl, n is 1, 2 or 3 and, if n is 1, R₄ is hydrogen or one of the groups ##STR32## in which R₅ is C₁ -C₁₇ -alkyl, cyclohexyl or phenyl, R₆ is C₂ -C₁₈ -alkyl, C₆ -C₁₀ -cycloalkyl or a group of the formula (II) with R₁ being hydrogen or methyl, R₈ is C₂ -C₁₂ -alkyl, cyclohexyl or a group of the formula (II) with R₁ being hydrogen or methyl, R₉ is hydrogen, R₁₀ is C₄ -C₁₂ -alkyl or cyclohexyl, R₁₃ and R₁₄, which can be identical or different, are C₁ -C₁₂ -alkyl, cyclohexyl, allyl or a group of the formula (II) with R₁ being hydrogen or methyl, and X and Y, which can be identical or different, are a group ##STR33## where R₁₆ is hydrogen, C₁ -C₁₂ -alkyl, cyclohexyl, allyl or a group of the formula (II) with R₁ being hydrogen or methyl and, if n is 2, R₄ is one of the groups ##STR34## in which R₁₇ is C₄ -C₁₀ -alkylene, C₆ -C₈ -cycloalkylene or a group of the formula (IV) in which R₂₃ is hydrogen, R₁₈ is a direct bond, C₁ -C₈ -alkylene, C₂ -C₈ -alkylidene, cyclohexylene or phenylene, R₁₉ and R₂₁ are hydrogen, R₂₀ is C₆ -C₉ -alkylene or C₆ -C₁₃ -arylene, R₂₂ is C₁ -C₁₂ -alkyl, cyclohexyl, allyl or a group of the formula (II) with R₁ being hydrogen or methyl, and Z is --O-- or ##STR35## with R₁₆ being as defined above, and, if n is 3, R₄ is a 1,3,5-triazine-2,4,6-triyl group.

R₁ is preferably hydrogen, C₁ -C₄ -alkyl, allyl, benzyl or acetyl, in particular hydrogen or methyl.

Compounds of formula (I) wherein R₂ is hydrogen, C₁ -C₄ -alkyl, cyclohexyl, phenyl or benzyl and R₃ is phenyl unsubstituted or substituted by C₂ -C₄ -alkoxycarbonyl or is a group of the formula (II) are preferred.

Compounds of formula (I) wherein R₁ is hydrogen or methyl, R₂ is hydrogen or C₁ -C₄ -alkyl and R₃ is phenyl substituted by C₂ -C₄ -alkoxycarbonyl or is a group of formula (II) are particularly preferred.

Those compounds of formula (I) are of interest, wherein n is 1, 2 or 3 and, if n=1, R₄ is hydrogen, CN, ##STR36## in which R₅ is hydrogen, C₁ -C₁₈ -alkyl, cyclopentyl, cyclohexyl unsubstituted or substituted by C₁ -C₄ -alkyl, C₂ -C₁₈ -alkenyl, phenyl unsubstituted or substituted by C₁ -C₄ -alkyl, by C₁ -C₄ -alkoxy and/or by OH, C₇ -C₁₀ -phenylalkyl unsubstituted or substituted at the phenyl ring by C₁ -C₄ -alkyl and/or by OH, C₁ -C₁₀ -alkyl substituted by C₁ -C₁₈ -alkoxy, by C₂ -C₁₈ -dialkylamino or by a group of the formula (III) ##STR37## where R₁ is hydrogen, O.sup.., CN, NO, cyanomethyl, C₁ -C₁₂ -alkyl, C₃ -C₁₂ -alkenyl or C₃ -C₁₂ -alkynyl subject to the proviso that the carbon atom attached to the nitrogen atom is a primary carbon atom, C₇ -C₁₂ -aralkyl, C₁ -C₁₂ -acyl, 2,3-epoxypropyl, OH-monosubstituted C₂ -C₆ -alkyl or 2,3-dihydroxypropyl and W is --O-- or ##STR38## where R₁₅ is hydrogen, C₁ -C₁₈ -alkyl, cyclopentyl, cyclohexyl unsubstituted or substituted by C₁ -C₄ -alkyl, C₃ -C₁₈ -alkenyl, phenyl unsubstituted or substituted by C₁ -C₄ -alkyl, by C₁ -C₄ -alkoxy and/or by OH, C₇ -C₁₀ -phenylalkyl unsubstituted or substituted at the phenyl ring by C₁ -C₄ -alkyl and/or by OH, or is a group of the formula (II), R₆ is C₁ -C₁₈ -alkyl, C₂ -C₆ -alkyl substituted by OH, by C₁ -C₁₈ -alkoxy or by C₂ -C₁₈ -dialkylamino, cyclopentyl, cyclohexyl unsubstituted or substituted by C₁ -C₄ -alkyl, or is C₃ -C₁₈ -alkenyl, phenyl unsubstituted or substituted by C₁ -C₄ -alkyl and/or by C₁ -C₄ -alkoxy, C₇ -C₁₀ -phenylalkyl unsubstituted or substituted at the phenyl ring by C₁ -C₄ -alkyl and/or by OH, or is a group of the formula (II), R₇ is a direct bond, C₁ -C₁₈ -alkylene, C.sub. 2 -C₂₀ -alkylidene, C₇ -C₂₀ -phenylalkylidene, cyclohexylene unsubstituted or substituted by C₁ -C₄ -alkyl, C₂ -C₁₈ -alkenylene or phenylene, R₈ is as defined for R₆ or is hydrogen or an alkali metal, R₉ and R₁₀, which are identical or different, are as defined for R₁₅, or R₉ and R₁₀, together with the nitrogen atom to which they are bonded, form a pyrrolidine, piperidine, morpholine or hexahydroazepine group, R₁₁ is C₁ -C₁₂ -alkyl or phenyl unsubstituted or substituted by C₁ -C₃ -alkyl and/or by C₁ -C₃ -alkoxy, R₁₃ and R₁₄, which are identical or different, are as defined for R₆ or are hydrogen, and X and Y, which are identical or different, are a different bond, --O-- or ##STR39## where R₁₆ is as defined for R₁₅ or is OH-monosubstituted C₂ -C₆ -alkyl, or the groups R₁₃ X-- and R₁₄ Y--, which are identical or different, are a 1-pyrrolidinyl, 1-piperidyl, 4-morpholinyl, 1-hexahydroazepinyl or 4-methyl-1-piperazinyl group, or, if n=2, R₄ is ##STR40## in which R₁₇ is C₂ -C₁₈ -alkylene, C₄ -C₁₂ -alkylene substituted in the chain by 1 or 2 oxygen atoms, cyclohexylene, C₈ -C₁₈ -cyclohexylenedialkylene, C₁₃ -C₁₈ -alkylenedicyclohexylene, C₁₄ -C₁₈ -alkylidenedicyclohexylene, C₄ -C₈ -alkenylene, phenylene, xylylene or a group of the formula (IV) ##STR41## where R₂₃ is hydrogen, C₁ -C₄ -alkyl or phenyl, R₁₈ is a direct bond, C₁ -C₁₈ -alkylene, C₂ -C₂₀ -alkylidene, C₇ -C₂₀ -phenylalkylidene, cyclohexylene unsubstituted or substituted by C₁ -C₄ -alkyl, phenylene, C₂ -C₁₂ -alkylene substituted in the chain by 1 or 2 oxygen atoms or by 1 or 2 groups ##STR42## where R₂₄ is as defined for R₁₅, R₁₉ and R₂₁, which are identical or different, are as defined for R₁₅, R₂₀ in C₂ -C₁₈ -alkylene, cyclohexylene unsubstituted or substituted by C₁ -C₄ -alkyl, C₈ -C₁₈ -cyclohexylenedialkylene, C₁₃ -C₁₈ -alkylenedicyclohexylene, phenylene, xylylene, R₂₂ is as defined for R₁₃ and R₁₄, Z is as defined for X and Y, or --ZR₂₂ is 1-pyrrolidinyl, 1-piperidyl, 4-morpholinyl, 1-hexahydroazepinyl or 4-methyl-1-piperazinyl or halogen, R₂₅ is C₁ -C₄ -alkyl, or, if n=3, R₄ is C₄ -C₁₈ -alkanetrioyl unsubstituted or substituted by OH, N(CH₂ CO--)₃, benzenetricarbonyl or a group ##STR43## or is benzenetricarbamoyl or a 1,3,5-triazine-2,4,6-triyl group, a .tbd.P group, a .tbd.PO group or a group (--CO--R₇ --COO)₃ Al with R₇ as defined above.

n is preferably 1, 2 or 3, in particular 1 or 2.

Compounds of formula (I) wherein R₃ is a group of the formula (II) are preferred.

If n is 1, R₄ is in particular --COR₅, --COOR₆ or ##STR44## and if n is 2, R₄ is preferably ##STR45##

Those compounds of formula (I) are preferred, wherein n is 1, 2 or 3 and, if n=1, R₄ is selected from the group consisting of hydrogen, ##STR46## wherein R₅ is C₁ -C₁₈ -alkyl, R₆ is C₁ -C₁₈ -alkyl, C₂ -C₆ -alkyl substituted by C₁ -C₄ -alkoxy, cyclohexyl unsubstituted or substituted by C₁ -C₄ -alkyl or is a group of the formula (II), R₇ is C₁ -C₁₀ -alkylene, R₈ is hydrogen, R₉ and R₁₀ are independently hydrogen, C₁ -C₄ -alkyl or cyclohexyl, R₁₃ and R₁₄ are independently hydrogen, C₁ -C₈ -alkyl, allyl or a group of formula (II), X and Y are independently --O-- or ##STR47## R₁₆ is hydrogen, C₁ -C₈ -alkyl, OH-monosubstituted C₂ -C₄ -alkyl, allyl or a group of the formula (II), if n=2, R₄ is selected from the group consisting of --COO--R₁₇ --OOC--, ##STR48## wherein R₁₇ is C₂ -C₁₂ -alkylene or C₄ -C₁₂ -alkylene substituted in the chain by 1 or 2 oxygen atoms, R₁₈ is a direct bond or C₁ -C₁₀ -alkylene, R₁₉ and R₂₁ are hydrogen, R₂₀ is C₂ -C₁₀ -alkylene or cyclohexylene unsubstituted or substituted by C₁ -C₄ -alkyl, R₂₂ is C₁ -C₈ -alkyl, OH-monosubstituted C₂ -C₄ -alkyl or allyl, Z is --O-- or ##STR49## with R₁₆ being as defined above or --ZR₂₂ is halogen, R₂₅ is C₁ -C₄ -alkyl and, if n=3, R₄ is 1,3,5-triazine-2,4,6-triyl.

Those compounds of formula (I) are particularly preferred, wherein R₁ is hydrogen, R₂ is hydrogen or methyl, R₃ is 2,2,6,6-tetramethyl-4-piperidyl, n is 1, 2 or 3 and, if n is 1, R₄ is --COR₅, --COOR₆ or ##STR50## in which R₅ is C₁ -C₁₈ -alkyl, R₆ is C₁ -C₁₈ -alkyl, cyclohexyl, 4-t-butylcyclohexyl or 1,2,2,6,6-pentamethyl-4-piperidyl, R₁₃ and R₁₄ are independently C₁ -C₈ -alkyl or allyl, X and Y are independently --O-- or ##STR51## with R₁₆ being hydrogen, C₁ -C₈ -alkyl, allyl or 2,2,6,6-tetramethyl-4-piperidyl and, if n is 2, R₄ is ##STR52## in which R₁₇ is C₄ -C₆ -alkylene, R₁₈ is a direct bond or C₁ -C₈ -alkylene, R₂₂ is C₁ -C₈ -alkyl or allyl and Z is --O-- or ##STR53## with R₁₆ being as defined above and, if n is 3, R₄ is a 1,3,5-triazine-2,4,6-triyl group.

Those compounds of formula (I) are of interest, wherein R₁ is hydrogen, R₂ is hydrogen or methyl, R₃ is 2,2,6,6-tetramethyl-4-piperidyl, n is 1 or 2 and, if n is 1, R₄ is --COOR₆ or ##STR54## in which R₆ is C₄ -C₁₈ -alkyl, cyclohexyl, 4-t-butylcyclohexyl or 1,2,2,6,6-pentamethyl-4-piperidyl, R₁₃ and R₁₄ are independently C₁ -C₄ -alkyl, X and Y are ##STR55## with R₁₆ being 2,2,6,6-tetramethyl-4-piperidyl and, if n is 2, R₄ is ##STR56## in which R₁₇ is C₄ -C₆ -alkylene, R₂₂ is C₁ -C₄ -alkyl and Z is --O-- or ##STR57## with R₁₆ being hydrogen, C₁ -C₄ -alkyl or allyl.

Especially preferred examples of compounds of formula (I) are: ##STR58##

The compounds of the formula (I) may be obtained by two different procedures, depending on the nature of the group R₃, for example first preparing the compounds with n=1 and R₄ =H; from these, the compounds with n=1, 2, 3 or 4 and R₄ ≠H may be prepared by reaction with suitable acylating agents.

If R₃ is a group of the formula (II), the corresponding compounds of the formula (I) can be prepared for example in accordance with scheme 1, by reacting 2 moles of a piperidylamine (V) with 1 mol of an orthoester (VI) in which R' is C₁ -C₄ -alkyl, the amidine (VII) being formed with elimination of the alcohol R'OH. The compounds of the formula (I) with R₃ being a group of the formula (II) and R₄ ≠H may be then obtained from the compounds of the formual (VII) by acylation. ##STR59##

If R₃ is C₆ -C₁₈ -aryl, the corresponding compounds of the formula (I) can be prepared for example in accordance with scheme 2, by reacting a piperidylamine (V) with an alkylimidate (VIII) in which R' is as defined above, the amidine (IX) being formed with elimination of the alcohol R'OH.

The compounds of the formula (I) with R₃ =C₆ -C₁₈ -aryl and R₄ ≠H may be then prepared from the compounds of the formula (IX) by acylation. ##STR60##

The reaction (a) in schemes 1 and 2 can be carried out for example with or without an inert solvent, operating at a temperature from 80° to 250° C., preferably from 100° to 180° C., with removal of the alcohol liberated in the reaction.

The ratio of the reagents is not critical, and it is possible to use an excess of one or the other of the reagents.

The subsequent acylation reactions (b) in schemes (1) and (2) can be carried out preferably in an inert solvent at a temperature from -20° to 200° C., preferably from 0° to 180° C.; the reaction conditions depend on the type of acylating agent used.

If an acyl halide is used as the acylating agent, the hydrohalic acid liberated in the reaction is neutralized preferably with an inorganic base, such as e.g. sodium or potassium hydroxide or carbonate, in a quantity at least equivalent to the acid liberated in the reaction. The reactions according to schemes (1) and (2) can be carried out in a single reactor without isolation of the amidine (VII) or (IX), but it is also possible to separate these compounds off and to employ them after purification in the subsequent acylation reactions.

In order to illustrate the present invention more clearly, several examples of the preparation of compounds of the formula (I) are described below; these examples are given by way of illustration only and do not imply any restriction.

EXAMPLE 1

93.76 g (0.6 mol) of 2,2,6,6-tetramethyl-4-piperidylamine and 88.92 g (0.6 mol) of triethyl orthoformate are heated to 140°-150° C., with removal of the ethanol liberated in the reaction.

Heating is continued until the evolution of ethanol ceases. After cooling the precipitate formed is separated off by filtration, washed with n-hexane and dried. This gives the compound of the formula ##STR61## of melting point 175°-176° C.

Analysis for C₁₉ H₃₈ N₄ : Calculated: C 70.75%; H 11.87%; N 17.37%; Found: C 70.78%; H 11.96%; N 17.32%.

EXAMPLES 2 AND 3

Following the procedure of Example 1, and using the appropriate reagents, the following compounds of the general formula ##STR62## are prepared:

    ______________________________________                                                               Melting point                                            Example       R.sub.2 (°C.)                                             ______________________________________                                         2             CH.sub.3 --                                                                            93-94                                                    3             C.sub.2 H.sub.5 --                                                                     45-46                                                    ______________________________________                                    

EXAMPLE 4

To a suspension of 32.25 g (0.1 mol) of N,N'-bis-(2,2,6,6-tetramethyl-4-piperidyl)-formamidine (prepared as described in Example 1) in 150 ml of dichloromethane, cooled to 0° to +5° C., a solution of 11.39 g (0.105 mol) of ethyl chloroformate in 30 ml of dichloromethane is added slowly, while not exceeding 10° C. After the end of the addition, the mixture is stirred for 2 hours, allowing the temperature to rise up to 20° C., and is then again cooled to about 5° C., and a solution of 4.4 g (0.11 mol) of sodium hydroxide in 30 ml of water is slowly added, while not exceeding 10° C. After the end of the addition, stirring is continued for 2 hours, allowing the temperature to rise up to 20° C.

The organic phase is separated off, washed with water, dried over Na₂ SO₄ and evaporated to dryness.

The residue obtained is crystallized from ethyl acetate.

This gives the compound of the formula ##STR63## of melting point 123°-124° C.

Analysis for C₂₂ H₄₂ N₄ O₂ : Calculated: C 66.96%; H 10.73%; N 14.20%; Found: C 66.65%; H 10.71%; N 14.06%.

EXAMPLES 5-28

Following the procedure of Example 4, and using the appropriate reagents, the following compounds of the general formula ##STR64## are prepared:

    ______________________________________                                                                                 Melt-                                  Ex-                                     ing                                    am-                                     point                                  ple  n     R.sub.2  R.sub.4             °C.                             ______________________________________                                          5   1     H        COOC.sub.4 H.sub.9  89-                                                                            90                                      6   1     H                                                                                        ##STR65##          172- 173                                7   1     H        COC.sub.7 H.sub.15  oil                                     8   2     H        COO(CH.sub.2).sub.4OOC                                                                             172-                                                                           173                                     9   2     H        CO(CH.sub.2).sub.8CO                                                                               148-                                                                           149                                    10   1     CH.sub.3 COOC.sub.2 H.sub.5  oil                                    11   1     C.sub.2 H.sub.5                                                                         COOC.sub.2 H.sub.5  oil                                    12   1     CH.sub.3 COOC.sub.4 H.sub.9  92-                                                                            94                                     13   1     H                                                                                        ##STR66##          157- 158                               14   2     H        COO(CH.sub.2).sub.6OOC                                                                             165-                                                                           167                                    15   2     H        COCO                262-                                                                           263                                    16   2     H        CO(CH.sub.2).sub.4CO                                                                               155-                                                                           156                                    17   1     H        COC.sub.17 H.sub.35 wax                                    18   2     H        CO(CH.sub.2).sub.2 CO                                                                              238-                                                                           240                                    19   1     H                                                                                        ##STR67##          125- 126                               20   1     H        COCH.sub.3          127-                                                                           129                                    21   1     H                                                                                        ##STR68##          55- 56                                 22   1     H        COOCH.sub.2 CH.sub.2 OCH.sub.3                                                                     94-                                                                            95                                     23   2     H        COO(CH.sub.2).sub.2 O(CH.sub.2).sub.2 OOC                                                          140-                                                                           141                                    24   2     H                                                                                        ##STR69##          162- 163                               25   1     H        COOC.sub.18 H.sub.37                                                                               69-                                                                            70                                     26   1     H        COOC.sub.14 H.sub.29                                                                               55-                                                                            56                                     27   1     H        COC.sub.11 H.sub.23 60-                                                                            62                                     28   1     H        CO(CH.sub.2).sub.2 COOH                                                                            185-                                                                           186                                    ______________________________________                                    

EXAMPLE 29

64.5 g (0.2 mol) of N,N'-bis-(2,2,6,6-tetramethyl-4-piperidyl)-formamidine are added slowly to a solution of 18.45 g (0.1 mole) of cyanuric chloride in 500 ml of xylene cooled to 10° C., maintaining the temperature between 10° and 15° C.

After the end of the addition, the mixture is heated for 2 hours at 50°-55° C., 53 g (0.5 mol) of anhydrous ground Na₂ CO₃ are added, and the mixture is heated for 3 hours at 70° C. and then filtered hot.

A white solid precipitates from the filtered solution, and this is separated off by filtration and dried.

This gives the compound of the formula ##STR70## of melting point 206°-207° C.

Analysis for C₄₁ H₇₄ ClN₁₁ : Calculated: Cl=4.69%; Found: Cl=4.71%.

EXAMPLE 30

158 g (0.49 mol) of N,N'-bis-(2,2,6,6-tetramethyl-4-piperidyl)-formamidine are added slowly to a solution of 27.7 g (0.15 mol) of cyanuric chloride in 300 ml of trimethylbenzene, maintaining the temperature at 25°-30° C.

The mixture is then heated for one hour to 100°-110° C., 18.9 g of powdered sodium hydroxide are added, and heating is continued under reflux for 12 hours with azeotropic removal of the water of reaction.

The mixture is diluted with 100 ml of trimethylbenzene, cooled and filtered.

The residue obtained after dryness is washed with water and then with methyl ethyl ketone, and then dried again.

This gives the compound of the formula ##STR71## of melting point 295°-296° C.

Analysis for C₆₀ H₁₁₁ N₁₅ : Calculated: C 69.12%; H 10.73%; N 20.15%; Found: C 68.77%; H 10.72%; N 20.01%.

EXAMPLES 34-43

Following the procedure of Example 30, and using the appropriate reagents, the following compounds of the general formula ##STR72## are prepared:

    __________________________________________________________________________     Example                                                                             A                    B            Melting point °C.                __________________________________________________________________________     31                                                                                   ##STR73##                                                                                           ##STR74##   224-225                                 32                                                                                   ##STR75##                                                                                           ##STR76##   176-177                                 33                                                                                   ##STR77##           C.sub.4 H.sub.9 O                                                                           236-237                                 34                                                                                   ##STR78##           (C.sub.2 H.sub.5).sub.2N                                                                    232-234                                 35                                                                                   ##STR79##           NHCH.sub.2 CHCH.sub.2                                                                       246-248                                 36   N(CH.sub.2 CHCH.sub.2).sub.2                                                                        N(CH.sub.2 CHCH.sub.2).sub.2                                                                198-200                                 37   NHCH.sub.2 CHCH.sub.2                                                                               NHCH.sub.2 CHCH.sub.2                                                                       159-160                                 38                                                                                   ##STR80##           OC.sub.3 H.sub.7 iso                                                                        226-227                                 39                                                                                   ##STR81##           N(CH.sub.3).sub.2                                                                           205-206                                 40                                                                                   ##STR82##           N(C.sub.4 H.sub.9).sub.2                                                                    199-200                                 41                                                                                   ##STR83##           N(CH.sub.2 CHCH.sub.2).sub.2                                                                215-216                                 42                                                                                   ##STR84##           N(CH.sub.2 CH.sub.2 OH).sub.2                                                               210-212                                 43   N(C.sub.2 H.sub.5).sub.2                                                                            N(C.sub.2 H.sub.5).sub.2                                                                    121-122                                 __________________________________________________________________________

EXAMPLE 44

165.2 g (1 mol) of ethyl 4-aminobenzoate and 296.4 g (2 mol) of triethyl orthoformate are heated for 2 hours at 110° C., separating off the ethanol liberated in the reaction. The excess triethyl orthoformate is removed by heating to 110° C. in vacuo (24 mbar). The mixture is cooled, diluted with 600 ml of n-hexane, heated under reflux for 30 minutes and then allowed to cool, and the solid which has separated out is filtered off, washed with 300 ml of hexane and dried.

55.3 g (0.25 mol) of ethyl (4-ethoxycarbonylphenyl)-formimidate thus obtained and 39 g (0.25 mol) of 2,2,6,6-tetramethyl-4-piperidylamine are heated for 6 hours at 100° C. After cooling, 200 ml of acetone are added and the mixture is filtered.

The product obtained is washed with acetone and dried.

This gives a compound of the formula ##STR85## of melting point 110°-111° C.

Analysis for C₁₉ H₂₉ N₃ O₂ : Calculated: C 68.85%; H 8.82%; N 12.68%; Found: C 68.89%; H 8.90%; N 12.80%.

EXAMPLE 45

A solution of 8.58 g (0.051 mol) of hexamethylene diisocyanate in 20 ml of toluene is added slowly to 33.15 g (0.1 mol) of N-(2,2,6,6-tetramethyl-4-piperidyl)-N'-(4-ethoxycarbonylphenyl)formamidine (prepared as described in Example 44), dissolved in 100 ml of toluene. The mixture is then heated for 4 hours at 80° C. and evaporated to dryness under reduced pressure (26.7 mbar). The solid obtained is crystallized from acetone.

This gives the compound of the formula ##STR86## of melting point 151°-152° C.

Analysis for C₄₆ H₇₀ N₈ O₆ : Calculated: C 69.15%; H 7.81%; N 12.40%; Found: C 69.01%; H 7.86%; N 12.28%.

EXAMPLES 46-48

Following the procedure of Example 45, and using the appropriate reagents, the following compounds are prepared:

    __________________________________________________________________________     Ex. Formula                                          Melting point                                                                  °C.                __________________________________________________________________________     46                                                                                  ##STR87##                                       172-173                   47                                                                                  ##STR88##                                       199-200                   48                                                                                  ##STR89##                                       168-169                   __________________________________________________________________________

EXAMPLE 49

To a suspension of 32.25 g (0.1 mol) of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-formamidine (prepared as described in Example 1) in 150 ml of dichloromethane, cooled to 0° to 5° C., a solution of 14.24 g (0.105 mol) of diethyl carbamoylchloride in 30 ml of dichloromethane is added slowly while not exceeding 10° C.

After addition, the mixture is stirred, heating under reflux for 8 hours.

Then the mixture is cooled to about 5° C. and a solution of 4.4 g (0.11 mol) of sodium hydroxide in 30 ml of water is slowly added, while not exceeding 10° C.

After addition, stirring is continued for 1 hour, allowing the temperature to rise up to 20° C.

The organic phase is separated off, washed with water and dried over Na₂ SO₄. The solvent is evaporated and the residue obtained is crystallized from n-hexane.

This gives the compound of the formula ##STR90## of melting point 90°-91° C.

Analysis for C₂₄ H₄₇ N₅₀ : Calculated: C 68.36%; H 11.23%; N 16.61%; Found: C 68.01%; H 11.20%; N 16.33%.

EXAMPLE 50

To a suspension of 80.60 g (0.25 mol) of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-formamidine (prepared as described in Example 1) in 600 ml of dichloromethane, cooled to 0° to 5° C., a solution of 43.10 g (0.25 mol) of diethylchlorophosphate in 100 ml of dichloromethane is added slowly, while not exceeding 10° C. After addition the mixture is stirred for 2 hours allowing the temperature to rise up to 20° C., and then it is cooled again to about 5° C.

A solution of 10.8 g (0.27 mol) of sodium hydroxide in 100 ml of water is slowly added, while not exceeding 10° C.

After addition, stirring is continued for 2 hours, allowing the temperature to rise up to 20° C.

The organic phase is separated off, washed with water, dried over Na₂ SO₄ and evaporated to dryness.

The residue obtained is crystallized from octane.

This gives the compound of the formula ##STR91## of melting point 104°-106° C.

Analysis for C₂₃ H₄₇ N₄ O₃ P monohydrate: Calculated: C 57.7%; H 10.4%; N 11.7%; Found: C 57.37%; H 10.37%; N 11.6%.

EXAMPLE 51

Following the procedure of Example 4, and using the appropriate reagents, the compound of the formula ##STR92## is prepared.

Boiling point: 186°-188° C. at 0.067 mbar.

As mentioned at the outset, the compounds of the formula (I) are very effective in improving the light stability, heat stability and oxidation stability of organic materials, preferably synthetic polymers, in particular polyolefins.

Examples of organic materials which can be stabilized with compounds of formula (I) are:

Polymers of monoolefins and diolefins, for example polyethylene (which may be crosslinked), polypropylene, polyisobutylene, poly-1-butene, polymethyl-1-pentene, polyisoprene or polybutadiene, and also polymers of cycloolefins, for example of cyclopentene or norbornene. Mixtures of the said polymers, for example mixtures of polypropylene with polyisobutylene.

Copolymers of monoolefins and diolefins with one another or with other vinyl monomers, for example ethylene/propylene, propylene/1-butene, propylene/isobutylene, ethylene/1-butene, propylene/butadiene, isobutylene/isoprene, ethylene/vinyl acetate, ethylene/alkyl acrylates, ethylene/alkyl methacrylates or ethylene/acrylic acid copolymers and their salts (ionomers) and terpolymers of ethylene with propylene and a diene such as hexadiene, dicyclopentadiene or ethylidenenorbornene.

Polystyrene and poly-(p-methylstyrene).

Copolymers of styrene or α-methylstyrene with dienes or acrylic derivatives, for example styrene/butadiene, styrene/acrylonitrile, styrene/ethyl methacrylate, styrene/butadiene/ethyl acrylate, styrene/acrylonitrile/methyl acrylate, high-impact strength mixtures of styrene copolymers and other polymers, for example a polyacrylate, a diene polymer or an ethylene/propylene/diene terpolymer, and block copolymers of styrene, for example styrene/butadiene/styrene, styrene/isoprene/styrene, styrene/ethylene/butylene/styrene or styrene/ethylene/propylene/styrene.

Graft copolymers of styrene, for example styrene of polybutadiene, styrene and acrylonitrile on polybutadiene, styrene and alkyl acrylates or methacrylates on polybutadiene, styrene and acrylonitrile on ethylene/propylene/diene terpolymers, styrene and acrylonitrile on polyacrylates or polymethacrylates, styrene and acrylonitrile on acrylate/butadiene copolymers, and also mixtures with the copolymers mentioned under the preceding heading, for example the mixtures known as ABS, MBS, ASA or AES polymers.

Halogen-containing polymers, such as polychloroprene, chlorinated rubbers, chlorinated or sulfochlorinated polyethylene, polymers and copolymers of epichlorohydrin, polymers of halogen-containing vinyl compounds, for example polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride and polyvinylidene fluoride, and also copolymers thereof, for example vinyl chloride/vinylidene chloride, vinyl chloride/vinyl acetate or vinylidene chloride/vinyl acetate copolymers.

Polymers derived from α,β-unsaturated acids and their derivatives, such as polyacrylates and polymethacrylates, polyacrylamides and polyacrylonitrile.

Copolymers of the monomers under the preceding heading, mixed with one another or with other unsaturated monomers, for example acrylonitrile/butadiene, acrylonitrile/alkyl acrylate, acryl-o-nitrile/alkoxyalkyl acrylate or acrylonitrile/vinyl halide copolymers or acrylonitrile/alkyl methacrylate/butadiene terpolymers.

Polymers derived from unsaturated alcohols and amines or their acyl or acetal derivatives, such as polyvinyl alcohol, polyvinyl acetate, polyvinyl stearate, polyvinyl benzoate, polyvinyl maleate, polyvinyl butyral, polyallyl phthalate or polyallylmelamine.

Homopolymers and copolymers of cyclic ethers, such as polyalkylene glycols, polyethylene oxide, polypropylene oxide or their copolymers with bis-glycidyl ethers.

Polyacetals, such as polyoxymethylene and the polyoxymethylenes containing ethylene oxide as a comonomer.

Polyphenylene oxides and sulfides, and mixtures of polyphenylene oxides with polystyrene.

Polyurethanes derived on the one hand from polyethers, polyesters or polybutadiene with hydroxyl end groups and, on the other hand, aliphatic or aromatic polyisocyanates, and also their precursors (polyisocyanates, polyols or prepolymers). Polyamides and copolyamides derived from diamines and dicarboxylic acids and/or aminocarboxylic acids or the corresponding lactams, such as nylon-4, nylon-6, nylon-6/6, nylon-6/10, nylon-11, nylon-12, poly-2,4,4-trimethylhexamethylene-terephthalamide or poly-m-phenylene-isophthalamide, and also their copolymers with polyethers, for example with polyethylene glycols, polypropylene glycols or polytetramethylene glycols.

Polyureas, polyimides and polyamide-imides.

Polyesters derived from dicarboxylic acids and diols and/or hydroxycarboxylic acids or corresponding lactones, such as polyethylene terephthalate, polybutylene terephthalate, poly-1,4-dimethylolcyclohexane terephthalate, poly-2,2-(4-hydroxyphenyl)-propane terephthalate and polyhydroxybenzoate, and also the block copolyetheresters derived from polyethers with hydroxyl end groups.

Polycarbonates and polyesater-carbonates.

Polysulfones, polyether-sulfones and polyether-ketones.

Crosslinked polymers derived from aldehydes on the one hand and phenols, ureas and melamines on the other hand, such as phenol/formaldehyde resins, urea/formaldehyde resins and melamine/formaldehyde resins.

Drying and non-drying alkyd resins.

Unsaturated polyester resins derived from copolyesters of saturated and unsaturated dicarboxylic acids with polyalcohols and vinyl compounds as crosslinking agents, and also their halogen-containing modifications of low inflammability.

Thermosetting acrylic resins derived from substituted acrylic esters, such as epoxy-acrylates, urethane-acrylates and polyester-acrylates.

Alkyd resins, polyester resins or acrylate resins mixed with melamine resins, urea resins, polyisocyanates or epoxide resins as crosslinking agents.

Crosslinked epoxide resins derived from polyepoxides, for example from bis-glycidyl ethers or cycloaliphatic diepoxides.

Natural polymers of the type of cellulose, rubber, gelatine and their derivatives with chemical polymer-homologous modifications, such as cellulose acetates, cellulose propionates and cellulose butyrates, or cellulose ethers such as methylcellulose.

Mixtures of the above polymers, for example PP/EPDM, nylon-6/EPDM or ABS, PVC/EVA, PVC/ABS, PVC/MBS, PC/ABS and PBTP/ABS.

The compounds of formula (I) are in particular useful in stabilizing polyethylen and polypropylen.

The compounds of the formula (I) can be mixed with the organic material in various proportions depending on the nature of the polymer, on the end use and on the presence of other additives.

In general, it is advantageous to employ from 0.01 to 5% by weight of the compounds of the formula (I), relative to the weight of the organic material, preferably from 0.05 to 1%.

The compounds of the formula (I) can be incorporated into the polymeric materials via various processes, such as dry blending in the form of powders, or wet mixing in the form of solutions or suspensions, or mixing in the form of a master-batch; in these operations, the polymer can be employed in the form of powder, granules, a solution, a suspension or in the form of a latex.

The polymers stabilized with the products of the formula (I) can be used for the preparation of moulded articles, films, tapes, fibres, monofilaments, surface-coatings and the like.

If desired, the stabilized compositions of this invention may optionally also contain for example from about 0.05 to about 5%, preferably from about 0.1 to about 2.5% by weight of various conventional additives, such as antioxidants, UV absorbers, nickel stabilizers, pigments, fillers, plasticizers, antistatic agents, flameproofing agents, lubricants, anti-corrosion agents, metal deactivators and others.

Examples of additives which can be mixed with the compounds of the formula (I) are in particular;

Antioxidants belonging to the following classes:

Alkylated monophenols, for example:

2,6-Di-t-butyl-4-methylphenol, 2-t-butyl-4,6-dimethylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,6-di-t-butyl-4-n-butylphenol, 2,6-di-t-butyl-4-i-butylphenol, 2,6-di-cyclopentyl-4-methylphenol, 2-(α-methylcyclohexyl)-4,6-dimethylphenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol and 2,6-di-t-butyl-4-methoxymethylphenol.

Alkylated hydroquinones, for example:

2,6-Di-t-butyl-4-methoxyphenol, 2,5-di-t-butylhydroquinone, 2,5-di-t-amylhydroquinone and 2,6-diphenyl-4-octadecyloxyphenol.

Thiobisphenols, for example:

2,2'-Thio-bis-(6-t-butyl-4-methylphenol), 2,2'-thio-bis-(4-octylphenol), 4,4'-thio-bis-(6-t-butyl-3-methylphenol) and 4,4'-thio-bis-(6-t-butyl-2-methylphenol).

Alkylidene-bisphenols, for example:

2,2'-Methylene-bis-(6-t-butyl-4-methylphenol), 2,2'-methylene-bis-(6-t-butyl-4-ethylphenol), 2,2'-methylene-bis-[4-methyl-6-(α-methylcyclohexyl)-phenol], 2,2'-methylene-bis-(4-methyl-6-cyclohexylphenol), 2,2'-methylene-bis-(6-nonyl-4-methylphenol), 2,2'-methylene-bis-[6-(α-methylbenzyl)-4-nonylphenol], 2,2'-methylene-bis-[6-(α,α-dimethylbenzyl)-4-nonylphenol], 2,2'-methylene-bis-(4,6-di-t-butylphenol), 2,2'-ethylidene-bis-(4,6-di-t-butylphenol), 2,2'-ethylidene-bis-(6-t-butyl-4-isobutylphenol), 4,4'-methylene-bis-(2,6-di-t-butylphenol), 4,4'-methylene-bis-(6-t-butyl-2-methylphenol), 1,1-bis-(5-t-butyl-4-hydroxy-2-methylphenyl)-butane, 2,6-bis-(3-t-butyl-5-methyl-2-hydroxybenzyl)-4-methylpenol, 1,1,3-tris-(5-t-butyl-4-hydroxy-2-methylphenyl)-butane, 1,1-bis-(5-t-butyl-4-hydroxy-2-methylphenyl)-3-n-dodecylmercaptobutane, ethylene glycol bis-[3,3-bis-(3'-t-butyl-4'-hydroxyphenyl-butyrate], bis-(3-t-butyl-4-hydroxy-5-methylphenyl)-dicyclopentadiene and bis-[2-(3'-t-butyl-2'-hydroxy-5'-methylbenzyl)-6-t-butyl-4-methylphenyl]terephthalate.

Benzyl compounds, for example:

1,3,5-Tris-(3,5-di-t-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, bis-(3,5-di-t-butyl-4-hydroxybenzyl)sulfide, isooctyl 3,5-di-t-butyl-4-hydroxybenzyl-mercaptoacetate, bis-(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)dithiolterephthalate, 1,3,5-tris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris-(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, dioctadecyl 3,5-di-t-butyl-4-hydroxybenzyl-phosphonate and calcium monoethyl 3,5-di-t-butyl-4-hydroxybenzyl-phosphonate.

Acylaminophenols, for example:

Lauric acid 4-hydroxyanilide, stearic acid 4-hydroxyanilide, 2,4-bis-(octylmercapto)-6-(3,5-t-butyl-4-hydroxyanilino)-s-triazine and octyl N-(3,5-di-t-butyl-4-hydroxyphenyl)-carbamate.

Esters of β-(3,5-di-t-butyl-4-hydroxyphenyl)-propionic acid with monohydric or polyhydric alcohols, for example:

Methanol, octadecanol, 1,6-hexanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris-(hydroxyethyl)-isocyanurate and N,N'-bis-(hydroxyethyl)-oxamide.

Esters of β-(5-t-butyl-4-hydroxy-3-methylphenyl)-propionic acid with monohydric or polyhydric alcohols, for example:

Methanol, octadecanol, 1,6-hexanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris-(hydroxyethyl)-isocyanurate and N,N'-bis-(hydroxyethyl)-oxamide.

Amides of β-(3,5-di-t-butyl-4-hydroxyphenyl)-propionic acid:

N,N'-Bis-(3,5-di-t-butyl-4-hydroxyphenylpropionyl)-hexamethylenediamine, N,N'-bis-(3,5-di-t-butyl-4-hydroxyphenylpropionyl)-trimethylenediamine and N,N'-bis-(3,5-di-t-butyl-4-hydroxyphenylpropionyl)-hydrazine.

UV absorbers and light stabilizers belonging to the following groups:

2-(2'-Hydroxyphenyl)-benzotriazoles, for example the 5'-methyl, 3',5'-di-t-butyl, 5'-t-butyl, 5'-(1,1,3,3-tetramethylbutyl), 5-chloro-3',5'-di-t-butyl, 5-chloro-3'-t-butyl-5'-methyl, 3'-sec.-butyl-5'-t-butyl, 4'-octoxy-3',5'-di-t-amyl and 3',5'-bis-(α,α-dimethylbenzyl) derivatives.

2-Hydroxybenzophenones, for example the 4-hydroxy, 4-methoxy, 4-octoxy, 4-decyloxy, 4-dodecyloxy, 4-benzyloxy, 4,2',4'-trihydroxy and 2'-hydroxy-4,4'-dimethoxy derivatives.

Esters of various substituted benzoic acids, for example:

Phenyl salicylate, 4-t-butylphenyl salicylate, octylphenyl salicylate, dibenzoylresorcinol, bis-(4-t-butylbenzoyl)-resorcinol, benzoylresorcinol, 2,4-di-t-butylphenyl 3,5-di-t-butyl-4-hydroxybenzoate, hexadecyl 3,5-di-t-butyl-4-hydroxybenzoate and N-ethyl-N-phenyl-N'-(p-ethoxycarbonylphenyl)-formamidine.

Acrylates, for example:

Ethyl or isooctyl α-cyano-β,β-diphenylacrylate, methyl α-carbomethoxycinnamate, methyl or butyl α-cyano-β-methyl-p-methoxycinnamate, methyl α-carbomethoxy-p-methoxycinnamate and N-(β-carbomethoxy-β-cyanovinyl)-2-methylindoline.

Nickel compounds, for example:

Nickel complexes of 2,2'-thio-bis-[4-(1,1,3,3-tetramethylbutyl)-phenol], such as the 1:1 or 1:2 complexes, which may contain additional ligands such as n-butylamine, triethanolamine or N-cyclohexyl-diethanolamine, nickel dibutyldithiocarbamate, nickel salts of the monoalkyl esters of 4-hydroxy-3,5-di-t-butylbenzylphosphonic acid, such as the methyl, ethyl or butyl esters, nickel complexes of ketoximes such as 2-hydroxy-4-methylphenyl undecyl ketoxime and nickel complexes of 1-phenyl-4-lauroyl-5-hydroxypyrazole with or without additional ligands.

Sterically hindered amines, for example:

Bis-(2,2,6,6-tetramethylpiperidyl)sebacate, bis-(1,2,2,6,6-pentamethylpiperidyl)sebacate,bis-(1,2,2,6,6-pentamethylpiperidyl) n-butyl-3,5-di-t-butyl-4-hydroxybenzylmalonate, the condensation product of 1-(hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, the condensation product of N,N'-bis-(2,2,6,6-tetramethylpiperidyl)hexamethylenediamine and 4-t-octylamino-2,6-dichloro-1,3,5-triazine, tris-(2,2,6,6-teramethylpiperidyl)nitrilotriacetate, tetrakis(2,2,6,6-tetramethylpiperidyl) 1,2,3,4-butanetetracarboxylate and 1,1'-(1,2-ethanediyl)-bis-(3,3,5,5-tetramethylpiperazinone).

Oxalic acid diamides, for example:

4,4'-Dioctyloxy-oxanilide, 2,2'-dioctyloxy-5,5'-di-t-butyloxanilide, 2,2'-didodecyloxy-5,5'-di-t-butyloxanilide, 2-ethoxy-2'-ethyloxanilide, N,N'-bis-(3-dimethylaminopropyl)-oxalamide, 2-ethoxy-5-t-butyl-2'-ethyloxanilide and its mixtures with 2-ethoxy-2'-ethyl-5,4'-di-t-butyloxanilide, and mixtures of ortho- and para-methoxy- and also o- and p-ethoxy-di-substituted oxanilides.

Metal deactivators, for example:

N,N'-diphenyloxamide, N-salicylal-N'-salicyloylhydrazine, N,N'-bis-(salicyloyl)-hydrazine, N,N'-bis-(3,5-di-t-butyl-4-hydroxyphenylpropionyl)-hydrazine, 3-salicyloylamino-1,2,4-triazole and bis-(benzylidene)-oxalodihydrazide.

Phosphites and phosphonites, for example:

Triphenyl phosphite,diphenyl alkyl phosphites, phenyl dialkyl phosphites, tris-(nonylphenyl)phosphite, trilauryl phosphite, trioctadecyl phosphite, distearyl pentaerythritol diphosphite, tris-(2,4-di-t-butylphenyl)phosphite, diisodecyl pentaerythritol diphosphite, di-(2,4-di-t-butylphenyl)pentaerythritol diphosphite, tristearyl sorbitol diphosphite and tetrakis-(2,4-di-t-butylphenyl) 4,4'-diphenylene-diphosphonite.

Peroxide-destroying compounds, for example:

Esters of β-thiodipropionic acid, for example the lauryl, stearyl, myristyl or tridecyl esters, mercaptobenzimidazole or the zinc salt of 2-mercaptobenzimidazole, zinc dibutyl-dithiocarbamate, dioctadecyl disulfide and pentaerythritol tetrakis-(β-dodecyl-mercapto)propionate.

Polyamide stabilizers, for example:

Copper salts in combination with iodides and/or phosphorus compounds and divalent manganese salts.

Basic costabilizers, for example:

Melamine, polyvinylpyrrolidone, dicyandiamide, triallyl cyanurate, urea derivatives, hydrazine derivatives, amines, polyamides, polyurethanes, alkali metal or alkaline earth metal salts of higher fatty acids, for example calcium stearate, zinc stearate, magnesium stearate, sodium ricinoleate and potassium palmitate, antimony pyrocatecholate or zinc pyrocatecholate.

Nucleating agents, for example:

4-T-butylbenzoic acid, adipic acid and diphenylacetic acid.

Fillers and reinforcing agents, for example:

Calcium carbonate, silicates, glass fibres, asbestos, talc, kaolin, mica, barium sulfate, metal oxides and hydroxides, carbon black and graphite.

Further additives, for example:

Plasticizers, lubricants, emulsifiers, pigments, fluorescent brighteners, flameproofing agents, antistatic agents and foaming agents.

The efficiency, as stabilizers, of the products prepared according to the invention, is illustrated in the examples which follow, in which some products obtained in the preparation examples are used for stabilizing polypropylene plates and tapes.

EXAMPLE 52

1 g of each of the compounds indicated in Table 1, 0.5 g of tris-(2,4-di-t-butylphenyl)phosphite, 0.5 g of pentaerythritol tetrakis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate], 1 g of Blue Phthalocyanine, 1 g of calcium stearate and 1,000 g of polypropylene powder (melt index=2.4 g/10 min; measured at 230° C. and 2,16 kp) are intimately mixed in a slow mixer. The mixtures obtained are extruded at a temperature of 200°-220° C. to give polymer granules which are then converted into plaques of 2 mm thickness by injection-moulding at 190°-220° C.

The plaques obtained are exposed in a model 65 WR Weather-O-Meter (ASTM G26-77) at a black panel temperature of 63° C. until the start of superficial embrittlement (chalking).

For comparison, a polypropylene plaque prepared under the same conditions as indicated above, but without the addition of the compounds of the invention, is exposed.

Table 1 shows the exposure time (in hours) required to reach the start of superficial embrittlement.

                  TABLE 1                                                          ______________________________________                                         Stabilizer       Embrittlement time (hours)                                    ______________________________________                                         Without stabilizer                                                                                500                                                         Compound of Example 4                                                                           4,300                                                         Compound of Example 5                                                                           4,800                                                         Compound of Example 6                                                                           4,000                                                         Compound of Example 8                                                                           3,600                                                         Compound of Example 13                                                                          3,800                                                         Compound of Example 21                                                                          3,750                                                         Compound of Example 49                                                                          3,900                                                         ______________________________________                                    

EXAMPLE 53

1 g of each of the compounds indicated in Table 2, 0.5 g of tris-(2,4-di-t-butylphenyl)phosphite, 0.5 g of pentaerythritol tetrakis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate] and 1 g of calcium stearate are mixed in a slow mixer with 1,000 g of polypropylene powder (melt index=3 g/10 min; measured at 230° C. and 2.16 kp).

The mixtures obtained are extruded at a temperature of 200°-220° C. to give polymer granules which are then converted into stretched tapes of 50 μm thickness and 2.5 mm width, using a semitechnical-scale apparatus (Leonard, Sumisago (VA)-Italy), under the following working conditions:

Extruder temperature: 220°-240° C.

Head temperature: 260° C.

Stretch ratio: 1:6

The tapes thus prepared are exposed, mounted on a white card, in a model 65 WR Weather-O-Meter (ASTM G26-77), with a black panel temperature of 63° C.

The residual tenacity is measured on samples, taken after various times of exposure to light, by means of a constant-speed tensometer; the exposure time in hours (T₅₀) needed to halve the initial tenacity is then calculated.

For comparison, tapes prepared under the same conditions as indicated above, but without the addition of the compounds of the invention, are exposed. The results obtained are shown in Table 2.

                  TABLE 2                                                          ______________________________________                                         Stabilizer         T.sub.50 (hours)                                            ______________________________________                                         Without stabilizer   190                                                       Compound of Example 10                                                                            2,710                                                       Compound of Example 13                                                                            2,150                                                       Compound of Example 14                                                                            2,500                                                       Compound of Example 18                                                                            2,200                                                       Compound of Example 20                                                                            2,100                                                       Compound of Example 21                                                                            2,400                                                       Compound of Example 33                                                                            2,800                                                       Compound of Example 34                                                                            3,150                                                       Compound of Example 46                                                                            2,450                                                       Compound of Example 49                                                                            2,300                                                       ______________________________________                                     

What is claimed is:
 1. A compound of formula I ##STR93## in which R₁ is hydrogen, O.sup.·, CN, NO, cyanomethyl, C₁ -C₁₂ -alkyl, C₃ -C₁₂ -alkenyl or C₃ -C₁₂ -alkynyl subject to the proviso that the carbon atom attached to the nitrogen atom is a primary carbon atom, C₇ -C₁₂ -aralkyl, C₁ -C₁₂ -alkanoyl, C₃ -C₁₂ -alkenoyl, C₃ -C₁₂ -alkynoyl, benzoyl or benzoyl substituted by one or more of C₁ -C₄ -alkyl or --OH 2,3-epoxypropyl, OH-monosubstituted C₂ -C₆ -alkyl or 2,3-dihydroxypropyl, R₂ is hydrogen, C₁ -C₁₈ -alkyl, C₅ -C₁₈ -cycloalkyl, C₆ -C₁₈ -aryl or C₇ -C₁₈ -aralkyl, R₃ is C₆ -C₁₈ -aryl or a group of the formula (II) ##STR94## in which R₁ is as defined above,n is an integer from 1 to 3, and R₄ is a triazinyl radical of a valency equal to n, with the proviso that when n is 1, R₄ is ##STR95## where R₁₃ and R₁₄ are independently C₁ -C₁₈ -alkyl, C₂ -C₆ -alkyl substituted by OH, by C₁ -C₁₈ -alkoxy or by C₂ -C₁₈ -dialkylamino; C₅ -C₁₈ -cycloalkyl, C₃ -C₁₈ -alkenyl, C₆ -C₁₈ -aryl, C₇ -C₁₈ -aralkyl or a group of formula II, or R₁₃ and R₁₄ are hydrogen, and X and Y are independently a direct bond, --O-- or ##STR96## where R₁₆ is hydrogen, C₁ -C₁₈ -alkyl, C₅ -C₁₈ -cycloalkyl, C₃ -C₁₈ -alkenyl, C₆ -C₁₈ -aryl, C₇ -C₁₈ -aralkyl or a group of formula II, or R₁₆ is OH-monosubstituted C₂ -C₆ -alkyl, or the groups R₁₃ X and R₁₄ Y are independently 1-pyrrolidinyl, 1-piperidyl or 4-methyl-1-piperazinyl, when n is 2, R4 is ##STR97## where R₂₂ is as defined for R₁₃ and R₁₄, Z is as defined for X and Y, or --ZR₂₂ is 1-pyrrolidinyl, 1-piperidyl, 4-methyl-1-piperazinyl or halogen, and when n is 3, R₄ is a 1,3,5-triazine-2,4,6-triyl group.
 2. A compound according to claim 1, in which R₁ is hydrogen, methyl, allyl, benzyl or acetyl, R₂ is hydrogen, C₁ -C₁₂ -alkyl, C₆ -C₉ -cycloalkyl or C₆ -C₉ -aryl, R₃ is C₆ -C₁₂ -aryl or a group of the formula (II), n is 1, 2 or 3 and, if n is 1, R₄ is ##STR98## in which R₁₃ and R₁₄, which are identical or different, are hydrogen, C₁ -C₁₂ -alkyl, C₆ -C₉ -cycloalkyl, allyl or a group of the formula (II), X and Y, which are identical or different, are --O-- or ##STR99## where R₁₆ is hydrogen, C₁ -C₁₂ -alkyl, C₆ -C₉ -cycloalkyl, allyl or a group of the formula (II), or the groups R₁₃ X-- and R₁₄ Y-- or which are identical or different, are a 1-pyrrolidinyl, 1-piperidyl, group or, if n is 2, R₄ is ##STR100## in which R₂₂ is hydrogen, C₁ -C₁₂ -alkyl, C₆ -C₉ -cycloalkyl, allyl or a group of the formula (II) and Z is --O-- or ##STR101## with R₁₆ as defined hereinabove, or, if n is 3, R₄ is a 1,3,5-triazine-2,4,6-triyl group.
 3. A compound according to claim 1, in which R₁ is hydrogen or methyl, R₂ is hydrogen or methyl, R₃ is 2,2,6,6-tetramethyl-4-piperidyl or 1,2,2,6,6-pentamethyl-4-piperidyl, n is 1, 2 or 3 and, if n is 1, R₄ is ##STR102## in which R₁₃ and R₁₄, which are identical or different, are C₁ -C₁₂ -alkyl, cyclohexyl, allyl or a group of the formula (II) with R₁ being hydrogen or methyl, and X and Y, which are identical or different, are a group ##STR103## where R₁₆ is hydrogen, C₁ -C₁₂ -alkyl, cyclohexyl, allyl or a group of the formula (II) with R₁ being hydrogen or methyl and, if n is 2, R₄ is ##STR104## in which R₁₇ is C₄ -C₁₀ -alkylene, C₆ -C₈ -cycloalkylene or a group of C₆ -C₁₃ -arylene, R₂₂ is C₁ -C₁₂ -alkyl, cyclohexyl, allyl or a group of the formula (II) with R₁ being hydrogen or methyl, and Z is --O-- or ##STR105## with R₁₆ being as defined hereinabove, and, if n is 3, R₄ is a 1,3,5-triazine-2,4,6-triyl group.
 4. A compound according to claim 1 wherein R₁ is hydrogen, C₁ -C₄ -alkyl allyl, benzyl or acetyl.
 5. A compound according to claim 1 wherein R₂ is hydrogen, C₁ -C₄ -alkyl, cyclohexyl, phenyl or benzyl and R₃ is phenyl unsubstituted or substituted by C₂ -C₄ -alkoxycarbonyl or is a group of the formula (II) in which R₁ is as defined in claim
 1. 6. A compound according to claim 1 wherein R₁ is hydrogen or methyl, R₂ is hydrogen or C₁ -C₄ -alkyl and R₃ is phenyl substituted by C₂ -C₄ -alkoxycarbonyl or is a group of formula (II) in which R₁ is as defined hereinabove.
 7. A compound according to claim 1 wherein n is 1 or
 2. 8. A compound according to claim 7 wherein n is
 1. 9. A compound according to claim 7 wherein n is
 2. 10. A compound according to claim 1 wherein n is 1, 2 or 3 and if n=1, R₄ is ##STR106## wherein R₁₃ and R₁₄ are independently hydrogen, C₁ -C₈ -alkyl, allyl or a group of formula (II) wherein R₁ is as defined in claim 1, X and Y are independently --O-- or ##STR107## R₁₆ is hydrogen, C₁ -C₈ -alkyl, OH--mono-substituted C₂ -C₄ -alkyl, allyl or a group of the formula (II) wherein R₁ is as defined in claim 1, if n=2, R₄ is ##STR108## and wherein R₂₂ is C₁ -C₈ -alkyl, OH-monosubstituted C₂ -C₄ -alkyl or allyl, Z is --O-- or ##STR109## with R₁₆ being as defined hereinabove or --ZR₂₂ is halogen, and, if n=3, R₄ is 1,3,5-triazine-2,4,6-triyl.
 11. A compound according to claim 1 wherein R₁ is hydrogen, R₂ is hydrogen or methyl, R₃ is 2,2,6,6-tetramethyl-4-piperidyl, n is 1, 2 or 3 and, if n is 1, R₄ is ##STR110## in which R₁₃ and R₁₄ are independently C₁ -C₈ -alkyl or allyl, X and Y are independently --O-- or ##STR111## with R₁₆ being hydrogen, C₁ -C₈ -alkyl, allyl or 2,2,6,6-tetramethyl-4-piperidyl and, if n is 2, R₄ is ##STR112## in which R₂₂ is C₁ -C₈ -alkyl or allyl and Z is --O-- or ##STR113## with R₁₆ being as defined hereinabove and, if n is 3, R₄ is a 1,3,5-triazine-2,4,6-triyl group.
 12. A compound according to claim 1, in which R₁ is hydrogen, R₂ is hydrogen or methyl, R₃ is 2,2,6,6-tetramethyl-4-piperidyl, n is 1 or 2 and, if n is 1, R₄ is ##STR114## in which R₁₃ and R₁₄ are independently C₁ -C₄ -alkyl, X and Y are ##STR115## with R₁₆ being 2,2,6,6-tetramethyl-4-piperidyl and, if n is 2, R₄ is ##STR116## in which R₂₂ is C₁ -C₄ -alkyl or allyl and Z is --O-- or ##STR117## with R₁₆ being hydrogen, C₁ -C₄ -alkyl or allyl.
 13. The compound ##STR118## according to claim
 1. 14. A composition of matter comprising a synthetic polymer subject to oxidative, thermal or light induced degradation stabilized with an effective stabilizing amount of a compound of claim
 1. 15. A composition according to claim 14, wherein the organic material is a polyolefin.
 16. A composition according to claim 15, wherein the polyolefin is polyethylene or polypropylene.
 17. A composition according to claim 14, which, in addition to the compound of formula (I), also comprises other conventional additives for synthetic polymers.
 18. A method for stabilizing a synthetic polymer against oxidative, thermal or light induced degradation which comprisesincorporating into said synthetic polymer an effective stabilizing amount of a compound according to claim
 1. 